Method of Fabricating an Antenna Having a Substrate Configured to Facilitate Through-Metal Energy Transfer Via Near Field Magnetic Coupling

ABSTRACT

An electrically conductive material configured having at least one opening of various unlimited geometries extending through its thickness is provided. The opening is designed to modify eddy currents that form within the surface of the material from interaction with magnetic fields that allow for wireless energy transfer therethrough. The opening may be configured as a cut-out, a slit or combination thereof that extends through the thickness of the electrically conductive material. The electrically conductive material is configured with the cut-out and/or slit pattern positioned adjacent to an antenna configured to receive or transmit electrical energy wirelessly through near-field magnetic coupling (NFMC). A magnetic field shielding material, such as a ferrite, may also be positioned adjacent to the antenna. Such magnetic shielding materials may be used to strategically block eddy currents from electrical components and circuitry located within a device.

RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.62/432,320, filed on Dec. 9, 2016, the disclosure of which is entirelyincorporated herein by reference.

TECHNICAL FIELD

The present disclosure generally relates to the wireless transmission ofelectrical energy and data. More specifically, this application relatesto various embodiments which enable the transmission of wirelesselectrical energy by near-field magnetic coupling through anelectrically conductive material.

BACKGROUND

Near field magnetic coupling (NFMC) is a commonly employed technique towirelessly transfer electrical energy. The electrical energy may be usedto directly power a device, charge a battery or both.

In near field magnetic coupling (NFMC) an oscillating magnetic fieldgenerated by a transmitting antenna passes through a receiving antennathat is spaced from the transmitting antenna, thereby creating analternating electrical current that is received by the receivingantenna.

However, when a magnetic field interacts with an electrically conductivematerial, such as a metal, a circulating eddy current is induced on thesurface of the conductive material as described by Faraday's Law. Theeddy current generated on the surface of the conductive materialgenerates a secondary magnetic field which opposes an incident magneticfield generated by the transmitting antenna. The interaction between theincident magnetic field generated by the transmitting antenna and theopposing secondary magnetic field, generated by the eddy current inducedin the metallic material, prevents the transmission of electrical energyfrom the transmitting antenna to the receiving antenna. Thus, theinclusion of a metallic substrate or backing with electronic devicesthat incorporate near field magnetic coupling wireless charging isprohibited. The interaction of the incident magnetic field with ametallic material comprising an exterior surface of a device preventsnear-field wireless electrical energy transmission with the device.

In addition, the circulating eddy current causes undesirable heating ofthe conductive material. Such heating may result in the loss of wirelessenergy but also could result in damage to the electrical componentswithin the device due to the increased heat. Currently, materials inwhich NFMC wireless energy can transmit through are limited tonon-conductive materials, such as glass, that do not deleteriouslyaffect the incident magnetic flux lines from a transmitting antenna.Incorporation of an electrically conductive material, such as a metal,within at least a portion of an exterior surface of a device, may berequired. Electrically conductive materials provide structural supportto such electronic devices as cellular phones, wearable devices, andmedical devices, all of which could benefit from wireless transfer ofelectrical energy through NFMC. Thus, there is a need for NFMC wirelessenergy transfer through a metallic material.

SUMMARY

The present disclosure relates to the transfer of wireless electricalenergy to and from devices that incorporate electrically conductivematerial, such as a metal. Such devices may include, but are not limitedto, consumer electronics, medical devices, and devices used inindustrial and military applications.

In one or more embodiments, an electrically conductive material, such asa metal substrate or plate is provided that is configured having atleast one opening that extends through its thickness. In one or moreembodiments, the electrically conductive material comprises at least aportion of an exterior surface of an electronic device. For example, theelectrically conductive material may comprise a device cover, a casing,a backing, or a device enclosure. In some embodiments, an electricallyconductive material is provided having a specific pattern of openingsthat extend through the thickness. Such a pattern of openings thatextend through the conductive material is designed to modify themagnitude and path of the induced eddy current on the surface of theelectrically conductive material to allow for wireless energy transfervia NFMC through the electrically conductive material.

In one or more embodiments, an opening, cut-out, slit, or combinationthereof is formed through the thickness of an electrically conductivematerial. This opening, cut-out or slit in its simplest form may beconfigured in a circular, ovular or a rectangular geometric shape.However, the opening may be configured in a plurality of non-limitinggeometric shapes or pattern of openings. For example, the opening maycomprise a logo, company name, or emblem of a product manufacturer. Inaddition, the opening may provide additional device functionality suchas an opening for a camera lens, a fingerprint sensor, or an opening foradditional device control or input port.

In one or more embodiments, the opening may comprise at least one slitthat extends through the thickness of the electrically conductivematerial and traverses from a location within the electricallyconductive material. In one or more embodiments, the at least one slitmay radially extend from a cut-out pattern to or through an edge of theelectrically conductive material, such as a metallic backing of adevice. The primary objective of the slit is to prevent the formation ofan eddy current loop on the surface of the electrically conductivematerial. Such eddy current loops on the surface of an electricallyconductive material disrupt wireless transmission of electrical energyvia NFMC.

Thus, by alternating the circulation path of the eddy current on thesurface of the electrically conductive material, the opposed magneticfields produced by the eddy current is modified, thereby allowing forwireless transmission of electrical energy through the electricallyconductive material via NFMC.

In one or more embodiments, a magnetic field shielding material, such asa ferrite material, may also be incorporated within the antennasub-assembly comprising the electrically conductive material with the atleast one cutout and slit. Such magnetic shielding materials may be usedto strategically block the opposing magnetic fields created by the eddycurrent, thus improving the amount and efficiency of the wirelesslytransmitted electrical energy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of wireless transmission of electricalenergy via near-field magnetic coupling between a transmitting antennaand a receiving antenna.

FIG. 2 shows an embodiment of the interaction between an incidentmagnetic field from a transmitting antenna and opposing magnetic fieldgenerated by an eddy current.

FIG. 3 illustrates an embodiment of a substrate of an electricallyconductive material through which a slit, a cut-out, or combinationthereof is configured to extend therethrough.

FIGS. 4 and 5 illustrate embodiments of antenna sub-assemblyconfigurations that may be used with an electrically conductivesubstrate having at least one cut-out and/or slit.

FIG. 6 illustrates an embodiment of an antenna coil and shieldingmaterial sub-assembly.

FIGS. 6A-6D illustrate cross-sectional views of different embodiments ofa receiving or transmitting antenna of the present disclosure withdifferent ferrite material shielding configurations.

FIGS. 7-10 illustrate embodiments of cut-outs configured in variousnon-limiting geometries.

FIGS. 11-19 illustrate embodiments of various non-limiting slitconfigurations.

FIGS. 20-24 illustrate embodiments of various non-limiting combinationsof cut-out and slit configurations.

FIGS. 25-28 illustrate embodiments of model simulated eddy currentdensities and direction vectors using various cut-out and slit patternsof the present disclosure.

FIG. 29 illustrates an embodiment of a simulated model that shows therelative direction of the eddy current and electrical energy wirelesslytransmitted from a transmitting antenna on the surface of anelectrically conductive substrate comprising a cut-out and slitconfiguration.

FIG. 30 shows an embodiment of the magnitude of the magnetic fields thatemanate perpendicularly from the surface of the electrically conductivesubstrate illustrated in FIG. 29.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth byway of examples in order to provide a thorough understanding of therelevant teachings. However, it should be apparent to those skilled inthe art that the present teachings may be practiced without suchdetails. In other instances, well known methods, procedures, components,and/or circuitry have been described at a relatively high-level, withoutdetail, in order to avoid unnecessarily obscuring aspects of the presentteachings.

The various embodiments illustrated in the present disclosure providefor the wireless transfer of electrical energy and/or data. Morespecifically, the various embodiments of the present disclosure providefor the wireless transfer of electrical energy and/or data via nearfield magnetic coupling through a metallic material, such as a metallicbacking or metallic casing of an electronic device.

Referring to FIG. 1, in inductive coupling, electrical power istransferred between a transmitting antenna 10 that is spaced from areceiving antenna 12 by an incident oscillating magnetic field 14. Theincident oscillating magnetic field 14 is generated by the transmittingantenna 10 and is received by the receiving antenna 12. An alternatingcurrent (AC) through the transmitting antenna 12 creates the incidentoscillating magnetic field 14 by Ampere's law. The incident oscillatingmagnetic field 14 passes through the receiving antenna 12, where itinduces an alternating electromotive force (EMF) voltage by Faraday'slaw of induction, which thus creates an alternating current in thereceiving antenna 12.

However, as illustrated in FIG. 2, when an oscillating magnetic field,such as an incident magnetic field 14 emanating from a transmittingantenna 10, interacts with an electrically conductive material 16, suchas a metal, a circulating eddy current 15 is induced on the surface ofthe conductive material 16 as described by Faraday's Law. Further, asecondary magnetic field 18, in opposition to the incident oscillatingmagnetic field 14, is generated by the circulating eddy currents asdescribed by Lenz's law. FIG. 2 illustrates this phenomenon in which anincident magnetic field 14 emanating from a transmitting antenna coil 20interacts with an electrically conductive material 16, such as a sheetof metal. As shown, the interaction of the incident magnetic field 14with the metal sheet causes an eddy current 15 to flow on the surface ofthe metal sheet in a clockwise direction. The formation of the eddycurrent on the metal sheet surface thus causes a secondary magneticfield 18 to emanate from the eddy current in an opposite direction tothat of the incident magnetic field 14 emanating from the coil of thetransmitting antenna 10. As a result, the secondary magnetic field 18generated by the eddy current negates at least a portion of the incidentmagnetic field 14 from the transmitting antenna 10, thereby causing themagnitude of the incident magnetic field 14 to be diminished orcancelled out. Therefore, wireless transmission of electrical energybetween the transmitting and receiving antennas 10, 12 is significantlyimpeded or prevented.

For example, if the incident magnetic field 14 from the transmittingantenna 10 is H₁, and the opposing secondary magnetic field 18 generatedby the eddy current emanating from the electrically conductive material16 is H₂, then the resultant magnetic field is H_(NET)=H₁−H₂. Thus, theinteraction of the two magnetic fields 14, 18 reduces or may cancel themagnitude of the incident magnetic field 14 emanating from thetransmitting antenna 10, thereby significantly reducing the amount orentirely blocking electrical energy from being wirelessly transmitted toa device 22 (FIG. 1) comprising the electrically conductive material.

In addition, the circulating eddy current may cause undesirable heatingof the electrically conductive material 16. Such heating may not onlyresult in loss of wireless energy but also could result in damage toother device components and circuitry due to the increased heat.Currently, materials through which NFMC wireless energy can transferwithout deleteriously affecting the magnetic flux lines are limited tonon-conductive materials, such as glass. However, such compatiblematerials are limited and may prevent desired device design andstructural performance attributes. Furthermore, in an environment withvarious materials with varying electrical and magnetic properties,multiple eddy current effects may be created that negatively affectwireless electrical energy transmission via NFMC and also may result inundesirable heating of the device 22.

The intensity and location of the opposing secondary magnetic fields 18depend on the magnitude and path of the eddy currents on the surface ofthe electrically conductive material 16. Thus, by creating appropriatecut-out and/or slit patterns that extend through the thickness of anelectrically conductive material, eddy current patterns are modifiedsuch that electrical energy is able to be transmitted wirelessly,efficiently and undisturbed through the material 16.

As will be discussed and illustrated in the various embodiments, thepresent disclosure provides for various opening configurations,including but not limited to a cut-out, a slit, or a combinationthereof, that alters the path of the eddy current on the surface of theelectrically conductive material 16 and thus mitigates the magnitude ofthe opposing secondary magnetic field 18 created by the eddy current. Asa result, the magnetic flux of the secondary magnetic field 18 issignificantly reduced in the area of the cut-out/slit pattern.Furthermore, the use of the cut-out and/or slit pattern of the presentdisclosure may intensify the eddy current within the cut-out/slitpattern. As a result, the magnetic flux of the incident magnetic field14 from the transmitting antenna 10 is increased in the cut-out/slitpattern. This increase in magnetic flux of the incident magnetic field14 from the transmitting antenna 10 increases mutual inductance betweenthe transmitting and receiving antennas 10, 12 and, in turn, increasesthe efficiency of wireless electrical energy transfer between the twoantennas.

In one or more embodiments, the present disclosure provides at least onesubstrate 24 as illustrated in FIG. 3 that comprises an electricallyconductive material, such as a metal. The substrate 24 may have at leastone opening of various configurations as illustrated in FIGS. 7 through24. In an embodiment, the opening may comprise a cut-out 30, as shown inFIGS. 7 through 10, a slit 32, as shown in FIGS. 11 through 19 or acombination thereof as shown in FIGS. 20 through 24.

In one or more embodiments, the slit 32, cut-out 30, or combinationthereof prevents the formation of an eddy current loop at the peripheryof the electrically conductive material 16. The formation of an eddycurrent loop at the periphery of an electrically conductive material 16disrupts the wireless transmission of electrical energy via NFMC. Inaddition, the cut-out 30 and/or slit 32 pattern changes the direction ofthe eddy current such that it creates a magnetic field having the samepolarity as the incident magnetic field 14 created by the transmittingantenna 10. This, therefore, helps to improve antenna-to-antennaefficiency.

In one or more embodiments, the cut-out 30 and/or slit 32 pattern of thepresent application is specifically designed to improve mutualinductance and transmitting antenna to receiving antenna efficiencywithout adding additional turns to the coil of the receiving antenna 12or increasing the permeability or thickness of a magnetic shieldingmaterial 34, such as a ferrite material, that may be positioned behindthe receiving antenna 12. As such, the present disclosure improves theefficiency of wireless energy transfer between the transmitting andreceiving antennas 10, 12 by decreasing the equivalent series resistance(ESR) and increasing the inductance and quality factor of the receivingantenna 12 that is positioned adjacent to an electrically conductivesubstrate 24 comprising the cut-out/slit pattern of the presentapplication.

In this application, the inventive concepts particularly pertain tonear-field magnetic coupling (NFMC). NFMC enables the transfer ofelectrical energy and/or data wirelessly through magnetic inductionbetween a transmitting antenna 10 and a corresponding receiving antenna12. The NFMC standard, based on near-field communication interface andprotocol modes, is defined by ISO/IEC standard 18092. Furthermore, asdefined herein “inductive charging” is a wireless charging techniquethat utilizes an alternating electromagnetic field to transferelectrical energy between two antennas. “Resonant inductive coupling” isdefined herein as the near field wireless transmission of electricalenergy between two magnetically coupled coils that are tuned to resonateat a similar frequency. As defined herein, “mutual inductance” is theproduction of an electromotive force in a circuit by a change in currentin a second circuit magnetically coupled to the first circuit.

As defined herein a “shielding material” is a material that captures amagnetic field. Examples of shielding material include, but are notlimited to ferrite materials such as zinc comprising ferrite materialssuch as manganese-zinc, nickel-zinc, copper-zinc, magnesium-zinc, andcombinations thereof. A shielding material thus may be used to direct amagnetic field to or away from an object, such as a parasitic metal,depending on the position of the shielding material within or nearby anelectrical circuit. Furthermore, a shielding material can be used tomodify the shape and directionality of a magnetic field. As definedherein a parasitic material, such as a parasitic metal, is a materialthat induces eddy current losses in the inductor antenna. This istypically characterized by a decrease in inductance and an increase inresistance of the antenna, i.e., a decrease in the quality factor. An“antenna” is defined herein as a structure that wirelessly receives ortransmits electrical energy or data. An antenna comprises a resonatorthat may comprise an inductor coil or a structure of alternatingelectrical conductors and electrical insulators. Inductor coils arepreferably composed of an electrically conductive material such as awire, which may include, but is not limited to, a conductive trace, afilar, a filament, a wire, or combinations thereof.

It is noted that throughout this specification the terms, “wire”,“trace”, “filament” and “filar” may be used interchangeably. As definedherein, the word “wire” is a length of electrically conductive materialthat may either be of a two dimensional conductive line or track thatmay extend along a surface or alternatively, a wire may be of a threedimensional conductive line or track that is contactable to a surface. Awire may comprise a trace, a filar, a filament or combinations thereof.These elements may be a single element or a multitude of elements suchas a multifilar element or a multifilament element. Further, themultitude of wires, traces, filars, and filaments may be woven, twistedor coiled together such as in a cable form. The wire as defined hereinmay comprise a bare metallic surface or alternatively, may comprise alayer of electrically insulating material, such as a dielectric materialthat contacts and surrounds the metallic surface of the wire. A “trace”is an electrically conductive line or track that may extend along asurface of a substrate. The trace may be of a two dimensional line thatmay extend along a surface or alternatively, the trace may be of a threedimensional conductive line that is contactable to a surface. A “filar”is an electrically conductive line or track that extends along a surfaceof a substrate. A filar may be of a two dimensional line that may extendalong a surface or alternatively, the filar may be a three dimensionalconductive line that is contactable to a surface. A “filament” is anelectrically conductive thread or threadlike structure that iscontactable to a surface. “Operating frequency” is defined as thefrequency at which the receiving and transmitting antennas operate.“Self-resonating frequency” is the frequency at which the resonator ofthe transmitting or receiving antenna resonates.

As defined herein a “slit” is an opening having a length, a widthoriented perpendicular to the length and a depth that extends throughthe substrate thickness, wherein the length is greater than the width. A“cut-out” or a “cut-out portion” is defined herein as an opening havingan area that is oriented about perpendicular to a depth that extendsthrough a substrate thickness. The area may be configured of a pluralityof geometric shapes that include, but are not limited to an oval, acircle, a square, a rectangle, a triangle, a hexagon, an octagon, or anynon-limiting polygon shape. In one or more embodiments, the area of theslit and “cut-out” are co-planar to a surface of the substrate that isperpendicular to the substrate thickness.

FIG. 3 illustrates one or more embodiments of the substrate 24 composedof an electrically conductive material through which the cut-out 30,slit 32 or combination thereof extends therethrough. As shown, thesubstrate 24 comprises a first substrate surface 36 opposed from asecond substrate surface 38, a thickness 28 extends therebetween. In oneor more embodiments, the thickness 28 of the substrate may range fromabout 0.01 mm to about 0.10 mm. The substrate 24 further comprises alength 40 and a width 42 oriented about perpendicular to the length 40.In one or more embodiments, the first and second substrate surfaces 36,38 comprises a perimeter 44 having an edge 46 that defines a first andsecond surface area of the respective first and second substratesurfaces 36, 38. In one or more embodiments, the substrate 24 comprisesan electrically conductive material, examples of which are not limitedto copper, aluminum, steel, and nickel.

FIG. 4 illustrates a cross-sectional view of one or more embodiments ofa stack up configuration of a wireless electrical energy receivingsub-assembly 52 comprising a receiving coil 54 of a receiving antenna12, a magnetic field shielding material 34, an electrically conductivesubstrate 24, and a second electrically conductive substrate 55. Asshown, the substrate 24 is configured with a cut-out 30. Alternatively,the substrate 24 may be configured with a slit 32 or a combination of aslit 32 and cutout 30. The sub-assembly 52 is designed to beincorporated within an electronic device 22 configured to beelectrically powered or electrically charged through transmission ofwireless electrical energy via NFMC. Examples of such electronic devices22 may include, but are not limited to a cellular phone, a radio, atelevision, a computer, a medical device, a device that comprises anelectronic circuit or any device that operates via electrical power.

In one or more embodiments, the substrate 24 comprising the cut-out 30,slit 32, or combination thereof of the present disclosure is positionedadjacent to the receiving coil 54 of a receiving antenna 12 configuredto receive electrical energy wirelessly transmitted via NFMC. As such,positioning the cut-out 30, slit 32, or a combination thereof adjacentto the receiving coil 54 of the receiving antenna 12 disrupts thecircular path of the eddy current on the surface of the electricallyconductive substrate 24. In addition, positioning the cut-out 30, slit32, or combination thereof adjacent to the receiving coil 54 of thereceiving antenna 12 allows for the eddy current 15 to flow within thecut-out and/or slit pattern in the same direction as the wirelesslytransmitted electrical energy, thus, the magnetic flux of the incidentmagnetic field 14 from the transmitting antenna 10 is increased as theincident magnetic field 14 travels through the cut-out and/or slitpattern of the electrically conductive substrate 24. Thus, theequivalent series resistance (ESR) of the receiving antenna 12 isreduced, and the inductance and quality factor of the receiving antenna12 is increased. As a result, mutual inductance and efficiency betweenthe transmitting and receiving antennas 10, 12 is increased whichenables efficient wireless transmission of electrical energy through theelectrically conductive substrate 24. It is further contemplated thatthe electrically conductive substrate 24 comprising the cut-out 30, slit32 or combination thereof, may be positioned adjacent to a transmittingcoil 20 of the transmitting antenna 10.

In one or more embodiments, as shown in FIG. 4, a gap 56 may bepositioned between the electrically conductive substrate 24 and thereceiving coil 54 of the receiving antenna 12. Alternatively, the gap 56may also be positioned between the electrically conductive substrate 24and the transmitting coil 20 of the transmitting antenna 10. In one ormore embodiments, the gap 56 separating the electrically conductivesubstrate 24 from the transmitting or receiving antenna coil 20, 54 mayextend from about 0.1 mm to about 10 mm. In one or more embodiments, thegap 56 between the receiving or transmitting coil 54, 20 reduces theproximity effect that may develop between the substrate 24 and thereceiving or transmitting coil 54, 20. Such a proximity effect maydegrade the mutual inductance between the transmitting and receivingantennas 10, 12.

In addition, a shielding material 34, such as a ferrite, may bepositioned facing a side of the transmitting or receiving antenna 10, 12opposite an opposite side facing the substrate 24 comprising thecut-out/slit pattern. In one or more embodiments, the shielding material34 may be positioned in contact with the transmitting or receivingantenna 10, 12 or may be spaced from the antenna by a shielding materialgap. In one or more embodiments, as illustrated in FIGS. 4 and 5, thecoil of the transmitting or receiving antenna 10, 12 may be positioneddirectly on a surface of the shielding material 34, such as a ferrite.In one or more embodiments, the shielding material 34 serves as thestructural support substrate in addition to preventing the interactionof the incident magnetic field 14 and the secondary magnetic field 18with the electrical components and circuitry of the device 22. In one ormore embodiments, when incorporated with the receiving antenna 12, theshielding material 34 may be used to minimize magnetic fields emanatingfrom the receiving coil 54. Such magnetic fields from the receiving coil54 may adversely interfere with the incident magnetic field 14 from thetransmitting antenna 10. In addition, as shown in FIG. 4, the secondelectrically conductive substrate 55 is positioned adjacent to themagnetic shielding material 34. As shown, the surface of the magneticshielding material 34, opposite the receiving coil 54, is in contactwith the second electrically conductive substrate 55. In one or moreembodiments, the second electrically conductive substrate 55 maycomprise a metal such as copper, aluminum, nickel, or a combinationthereof. The second electrically conductive substrate 55 may comprise abacking to provide structural support.

In one or more embodiments, the shielding material 34 may be a ferritematerial with a loss tangent as low as possible. In one or moreembodiments, the loss tangent of the ferrite material may be equal to orless than 0.70 at the antenna operating frequency. Such shieldingmaterials may include, but are not limited to, zinc comprising ferritematerials such as manganese-zinc, nickel-zinc, copper-zinc,magnesium-zinc, and combinations thereof. These and other ferritematerial formulations may be incorporated within a polymeric materialmatrix so as to form a flexible ferrite substrate. Examples of suchmaterials may include but are not limited to, FFSR and FFSX seriesferrite materials manufactured by Kitagawa Industries America, Inc. ofSan Jose, Calif. and Flux Field Directional RFIC material, manufacturedby 3M™ Corporation of Minneapolis, Minn. In one or more embodiments, thetransmitting or receiving antenna 10, 12 incorporated with the shieldingmaterial 34, such as a ferrite material, should have a self-resonancefrequency (SRF)>1.5 times the operating frequency, preferably an SRF>3times the operating frequency. For example, if the operating frequencyis 6.78 MHz, then the SRF of the antenna should be greater than 10 MHz.

In one or more embodiments, the transmitting or receiving antenna 10, 12may comprise at least one inductor coil such as the non-limitingexamples disclosed in U.S. Pat. App. Nos. 2017/0040690, 2017/0040692,2017/0040107, 2017/0040105, 2017/0040696, and 2017/0040688 all toPeralta et al., 2017/0040691, 2017/0040694 to Singh et al., 2017/0040693to Luzinski and 2017/0040695 to Rajagopalan et al., all of which areassigned to the assignee of the present application and incorporatedfully herein. In addition, the transmitting or receiving antenna 10, 12may be configured in a multi-layer-multi-turn (MLMT) construction inwhich at least one insulator is positioned between a plurality ofconductors. Non-limiting examples of antennas having an MLMTconstruction that may be incorporated with the present disclosure may befound in U.S. Pat. Nos. 8,610,530, 8,653,927, 8,680,960, 8,692,641,8,692,642, 8,698,590, 8,698,591, 8,707,546, 8,710,948, 8,803,649,8,823,481, 8,823,482, 8,855,786, 8,898,885, 9,208,942, 9,232,893,9,300,046, all to Singh et al., and assigned to the assignee of thepresent application are incorporated fully herein. It is also noted thatother antennas such as, but not limited to, an antenna configured tosend and receive signals in the UHF radio wave frequency such IEEEstandard 802.15.1 may be incorporated within the present disclosure.

In one or more embodiments, the inductor coils 20, 54 of either thetransmitting or receiving antennas 10, 12 are strategically positionedto facilitate reception and/or transmission of wirelessly transferredelectrical power or data through near field magnetic induction. Antennaoperating frequencies may comprise all operating frequency ranges,examples of which may include, but are not limited to, about 100 kHz toabout 200 kHz (Qi interface standard), 100 kHz to about 350 kHz (PMAinterface standard), 6.78 MHz (Rezence interface standard), oralternatively at an operating frequency being employed by a device in aproprietary recharging mode. In addition, the antenna 10, 12 of thepresent disclosure may be designed to receive or transmit over a widerange of operating frequencies on the order of about 1 kHz to about 1GHz or greater, in addition to the Qi and Rezence interfaces standards.

FIG. 5 illustrates one or more embodiments of a stack up configurationof a wireless electrical energy receiving sub-assembly 52. In one ormore embodiments, the wireless electrical energy receiving sub-assembly52 may be incorporated within an electronic device 22 configured to beelectrically powered or electrically charged through transmission ofwireless electrical energy via near-field magnetic coupling (NFMC). Asshown, the stack-up configuration comprises a receiving antenna coil 54positioned directly on a surface of a shielding material 34, i.e., aferrite material. The shielding material 34 and the receiving antennacoil 54 are sandwiched between a first electrically conductive substrate60 located at a stack-up proximal end 62 and an electrically insulativesubstrate 64 located at a stack-up distal end 66. In an embodiment, aspacer 68 composed of an electrically insulative material, such as apolymeric material, may be positioned between the first electricallyconductive substrate 60 and the receiving antenna coil 54. In one ormore embodiments, a second electrically conductive substrate 70 may bepositioned between the shielding material 34 and the electricallyinsulative substrate 64. As shown in FIG. 5, the first electricallyconductive substrate is configured with a cut-out 30. Alternatively, thefirst electrically conductive substrate 60 may be configured with a slit32 or a combination of a slit 32 and a cutout 30. In one or moreembodiments, the spacer 68 is a substrate composed of an electricallyinsulative material, such as a polymeric material. In one or moreembodiments, the spacer 68 serves to provide a gap between the receivingantenna coil 54 and the first electrically conductive substrate 60. Inone or more embodiments, the spacer 68 is designed to minimize theproximity effect between the inductor coil 54 and the first substrate60. Positioning the first substrate 60 adjacent to the receiving antennacoil 54, may cause a proximity effect to develop between the receivingantenna coil 54 and the first substrate 60 that may increase theelectrical resistance, i.e., ESR, of the receiving antenna coil 54.Thus, by positioning the electrically non-conductive polymer spacer 68between the first substrate 60 and the receiving antenna coil 54, theproximity effect between the receiving antenna coil 54 and the firstsubstrate 60 is reduced and the inductance of the receiving antenna coil54 does not decrease. In one or more embodiments, the spacer 68 may havea thickness that ranges from about 0.1 mm to about 10 mm.

In one or more an embodiments, the electrically insulative substrate 64is positioned adjacent to the second electrically conductive substrate70 opposite the side contacting the shielding material 34. In one ormore embodiments, the second electrically conductive substrate 70 iscomposed of an electrically conductive material, non-limiting examplesinclude, but are not limited to copper, nickel, aluminum or acombination thereof. In one or more embodiments, the second electricallyconductive substrate 70 may comprise a structural backing, a printedcircuit board (not shown) or a sidewall of a battery (not shown). Theelectrically insulative substrate 64 is intended to provide mechanicalstability to the structure of the sub-assembly stack-up configuration.

FIG. 6 illustrates one or more embodiments of a coil and shieldingmaterial sub-assembly 74. The coil may be a receiving coil 54 or atransmitting coil 20. Both coils may be similarly constructed. As shown,a coil 20, 54 comprising a plurality of filars arranged with at leastone turn, is positioned directly on a surface of the shielding material34, i.e., a ferrite material. In one or more embodiments, the coil 20,54 is positioned on the surface of the shielding material 34 such thatan overhang 76 of the shielding material 34 extends circumferentiallyaround an outer diameter 78 of the coil 20, 54. In one or moreembodiments, the overhang 76 may extend from about 0.5 mm to about 5 mm.Thus, by extending the length and width of the shielding material 34with respect to the position of the coil 20, 54 to the overhang 76,opposing magnetic fields that are generated by the coil 20, 54 arediminished. Thus, an increase in inductance and mutual inductance of theantenna is achieved.

As further illustrated in FIG. 6, the shielding material 34 may comprisean opening 80 that extends through the thickness of the shieldingmaterial 34. The coil 20, 54 is positioned circumferentially around theopening 80. Such a shielding material configuration comprising theopening 80 may be beneficial in applications where the coil 20, 54 andthe shielding material sub-assembly 74 are positioned at a distance frommetallic objects. Constructing the shielding material 34 with an opening80 that extends through the thickness of the shielding material 34decreases the electrical resistance of the coil 20, 54. However, theopening 80 in the shielding material 34 may decrease the inductance ofthe coil 20, 54. Therefore, the shielding material opening 80 should bedimensioned accordingly to meet the requirements of the application.

FIGS. 6A, 6B, 6C, and 6D are cross-sectional views illustrating variousembodiments in which a transmitting inductor coil 20 or a receivinginductor coil 54 comprising an electrically conductive trace 82 may beconstructed using materials that shield the inductor coils 20, 54 frommagnetic fields 106. It is noted that the embodiments shown in FIGS.6A-6D may comprise a transmitting inductor coil 20 or a receivinginductor coil 54. Furthermore, in one or more embodiments, the inductorcoil 20, 54 comprises an interior inductor coil 84 surrounded by anouter inductor coil 86. In one or more embodiments as illustrated in thecross-sectional views of FIGS. 6A-6D, first and second segments 88, 90comprise the outer inductor coil 86 and third and fourth segments 92, 94comprise the inner inductor coil 84.

As shown in the various embodiments, three different magnetic shieldingmaterials such as, a first material 96, a second material 98 and a thirdmaterial 100, each having a different permeability, loss tangent, and/ormagnetic flux saturation density may be used in the construction of theantenna of the present disclosure. In one or more embodiments, the firstmaterial 96 may comprise at least one of the FFSX series of ferritematerials having a permeability of about 100 to about 120 across afrequency range of at least 100 kHz to 7 MHz. The second material 98 maycomprise the RFIC ferrite material having a permeability of about 40 toabout 60, and the third material 100 may also comprise a ferritematerial or combinations thereof, as previously mentioned. In one ormore embodiments, the first 96, second 98, or third 100 materials maycomprise a permeability greater than 40. More preferably, the first 96,second 98, or third 100 materials may comprise a permeability greaterthan 100. The magnetic flux saturation density (Bsat) is at least 380mT.

FIG. 6A shows one or more embodiments in which the inductor coils 84,86, are positioned directly on an exterior surface of the ferritematerials. As shown, the first and second ferrite materials 96, 98 serveas substrate layers on which the inductive coils are positioned. Thethird ferrite material 100 is preferably positioned within a centrallocation between the coil winding, i.e., between the third and fourthinductor coil segments 92, 94. Note that each inductor coil segmentcould represent multiple traces of inductor coil turns. In one or moreembodiments the first and second segments 88, 90 of the outer inductivecoil 86 are shown positioned directly on a surface of a first layer ofthe first ferrite material 96 and the interior coil segments 92, 94 ofthe interior inductive coil 84 are positioned directly on the surface ofa second layer of the second ferrite material 98. The second layer ofthe second ferrite material 98 is positioned on top of the first layerof the first ferrite material 96. A third layer of the third ferritematerial 100 is positioned directly on the second layer of the secondferrite material 98. In one or more embodiments, the first, second andthird layers of the different ferrite materials 96, 98, and 100 arepositioned such that magnetic fields 106 generated by the inductivecoils 20, 54 are absorbed by the ferrite materials. Furthermore, theselection of the ferrite material may be based on the material used toconstruct the conductive lines as well as the amount of the current orvoltage flowing therethrough.

In one or more embodiments, the various magnetic shielding materials 34and structures could be used to create a hybrid magnetic shieldingembodiment. In a hybrid magnetic shielding embodiment, various ferritematerials are strategically positioned to improve the performance of themultiple inductor coils 20, 54 which resonate at differing frequencies.Thus, the ferrite materials are positioned to enhance the operation ofthe transmitting or receiving antenna 10, 12. For example, utilizing aferrite material having an increased permeability of about 100 to 120,such as the FFSX series material may be used to optimally shield a coilresonating at 6.78 MHz without degrading the performance of another coilresonating at a lower frequency range of 100 kHz to about 500 kHz.Likewise, utilization of a ferrite material having a lower permeabilitysuch as from about 40 to about 60, like the RFIC material, is preferredbecause it enhances the operation of a coil 20, 54 resonating in thelower kHz frequency region without degrading the performance of aninductor coil 20, 54 resonating in the MHz frequency range.

In addition to the specific ferrite material, the positioning of theferrite material is also important to the optimal operation of theantenna of the present disclosure. For example with reference to FIGS.6A through 6D, it may be preferred to position a higher permeabilityferrite material near an inductor coil 20, 54 configured to resonate ata higher frequency, such as the relative location of the first ferritematerial 96 as shown in FIGS. 6A-6D. Similarly, it may be beneficial toposition a ferrite material having a lower permeability near an inductorcoil 20, 54 configured to resonate in the kHz range such as the locationof the second ferrite material 98. The third ferrite material 100 couldbe a material that has similar properties as the second ferrite material98 or, alternatively, the third ferrite material 100 could be a materialthat has a high magnetic saturation that preserves the magneticperformance of the other materials in the presence of an antenna. Forexample, an antenna that comprises a magnet. In one or more embodiments,the various ferrite materials 96, 98, and 100 may act as an attractor tohelp affix to inductor coils 20, 54 that comprise a magnet.

FIG. 6B illustrates one or more embodiments of the construction of theantenna of the present disclosure in which the second ferrite material98 is positioned within a cavity 102 formed within the first ferritematerial 96. In addition, the height of the second ferrite material 98is greater than the height of the first ferrite material 96.

FIG. 6C illustrates one or more embodiments in which the second ferritematerial 98 is positioned within a cavity 102 formed within the firstferrite material 96. However, in contrast to the embodiments shown inFIGS. 6A and 6B, the height of the respective first and second ferritematerials 96, 98 are about equal. Lastly, FIG. 6D shows one or moreembodiments in which the third ferrite material 100 may be positionedwithin a second cavity 104 positioned within the second material layer98. In addition, the second material 98 is positioned within the firstcavity 102 formed within the first material 96. Furthermore, as shown inFIG. 6D, all three ferrite materials 96, 98 and 100 are positioned sothat they are of about the same height. Specifically as shown, the thirdmaterial 100 is positioned within the second cavity 104 of the secondferrite material 98, the second ferrite material 98 is positioned withinthe first cavity 102 of the first ferrite material 96 with all threeferrite material 96, 98, 100 being of about equal height. Therefore, thevarious ferrite materials may be positioned at different heightsrelative to each other such that magnetic fields 106 generated byadjacent conductive lines are optimally absorbed by the ferritematerials.

In addition to utilizing three ferrite materials as previouslydiscussed, it is contemplated that mixtures or compounds of variousferrite materials may be used to further custom tailor the desiredpermeability. Furthermore, the various layers may be composed of ferritematerial mixtures and alloys. It is also noted that FIGS. 6A-6Drepresents specific embodiments in which ferrite materials may bepositioned within the structure of the antenna of the presentdisclosure. It is contemplated that the various first, second, and thirdferrite materials 96, 98, 100 can be interchangeably positionedthroughout the structure of the antenna to custom tailor a desiredresponse or create a specific magnetic field profile.

In one or more embodiments, the electrically conductive substrate 24comprising the at least one cut-out 30 and slit 32 of the presentdisclosure may serve as a casing, enclosure or backing such as asidewall of a device 22 that at least partially encases the electricalcomponents and circuitry of an electronic device 22. Alternatively, theelectrically conductive substrate 24 comprising the at least one cut-out30 and slit 32 may be positioned internal to an electronic device 22.

FIGS. 7 through 10 are perspective views that illustrate embodiments ofthe various non-limiting geometric shapes in which the cut-out 30 may beconfigured. FIG. 7 illustrates a cut-out 30 configured in a circularshape. FIG. 8 illustrates a cut-out 30 configured in a rectangularshape. FIG. 9 shows a cut-out 30 configured in a triangular shape andFIG. 10 illustrates a cut-out 30 configured in a pentagon shape.

In one or more embodiments, a perimeter 108 of the cut-out 30 (FIG. 7)should align with an inner diameter 110 (FIG. 6) of the inductor coil54, 20 of the receiving or transmitting antenna 12, 10. For example, ifthe cut-out 30 is of a circular configuration with a diameter of about20 mm, the inductor coil 54 of the receiving antenna 12, positionedadjacent to the cut-out 30, should have a coil diameter 110 of about 20mm. In one or more embodiments, the diameter of the circular cut-outshape 30 should be positioned such that it is parallel to the innerdiameter 110 of the coil pattern 20, 54 of the transmitting or receivingantenna 10, 12. In other words, the shape of the inductor coil 20, 54 ofthe transmitting or receiving antenna 10, 12 should be configured toclosely mirror the geometric configuration of the cut-out 30 and bepositioned such that the cut-out 30 and the inductor coil 20, 54 areparallel to each other. In one or more embodiments, the inductor coil20, 54 and the electrically conductive substrate 24 comprising thecut-out 30 are aligned in parallel such that an imaginary line orientedperpendicular therebetween extends through a first point 112 (FIG. 7)that lies on the perimeter 108 of the cut-out 30 and a second point 114(FIG. 6) that lies on the inner diameter 110 of the inductor coil 20,54. An example of the alignment between the cut-out 30 and the receivingcoil 54 is shown in FIGS. 4 and 5.

FIGS. 11 through 19 are perspective views that illustrate embodiments ofvarious slit configurations. As illustrated the slit 32 comprises a slitlength 116 oriented about perpendicular to a slit width 118. In one ormore embodiments, at least one slit 32 may extend through the thickness28 of the electrically conductive substrate 24. In one or moreembodiments, the at least one slit 32 may be positioned in a parallel orperpendicular orientation with respect to either the length 40 or width42 of the electrically conductive substrate 24. In addition, the atleast one slit 32 may be oriented at a slit angle with respect to thelength 40 or width 42 of the electrically conductive substrate 24. Inone or more embodiments, the length 116 of the at least one slit 32 mayextend from about 10 mm to about 50 mm and the width 118 of the at leastone slit 32 may range from about 1 mm to about 5 mm. FIG. 11 illustratestwo slits 32 in a perpendicular orientation with respect to thesubstrate width 42. FIG. 12 shows three slits 32 that are in a parallelorientation with respect to the substrate width 42. In one or moreembodiments, at least one slit 32 extends through the thickness 28 ofthe electrically conductive substrate 24 and traverses through thethickness 28 from a proximal slit end 116 at a point 122 that resideswithin the substrate perimeter 44 to a distal slit end 124 that residesat the substrate edge 46. In one or more embodiments, the distal end 124of the at least one slit 32 may extend proximal of the edge 46, asillustrated in FIGS. 11 and 12 or may extend to the edge 46. Inaddition, the distal end 124 of the at least one slit 32 may extendthrough the edge 46 of the substrate 24 as shown in FIG. 13.

The primary objective of the at least one slit 32 is to prevent theformation of an eddy current loop on the surface of the electricallyconductive substrate 24. Preventing the formation of the eddy currentloop on the surface of the electrically conductive substrate 24 preventsthe formation of the eddy current secondary magnetic field 18 whichopposes the incident magnetic field 14 from the transmitting antenna 10which disrupts the wireless transmission of the electrical energy viaNFMC. In one or more embodiments, the at least one slit 32 extendsthrough the edge 46 of the electrically conductive substrate 24 and“cuts” the eddy current loop, thereby preventing formation of the eddycurrent secondary magnetic field 18 in opposition to the incidentmagnetic field 14.

FIG. 13 shows a slit 32 oriented in a perpendicular orientation withrespect to the substrate width 42 that extends through the edge 46defined by the perimeter 44 of the substrate 24. FIG. 14 illustratesthree spaced apart slits 32 that are arranged in a parallel orientationwith respect to the substrate width 42. As shown, two of the slits 32reside within the perimeter 44 of the substrate 24 whereas one of theslits 32 extends through the substrate edge 46.

FIGS. 15 and 16 illustrate one or more embodiments in which a pluralityof slits 32 may be arranged in a crisscross pattern. As illustrated inFIG. 15, three spaced apart slits 32 are positioned in a parallelorientation with respect to the substrate width 42. A fourth slit 32positioned in a perpendicular orientation with respect to the substratewidth 42 extends through the edge 46 of the substrate 24 and intersectsthe three spaced apart parallel oriented slits 32. As illustrated inFIG. 16, three spaced apart slits 32 are positioned in a parallelorientation with respect to the substrate width 42 and are arrangedparallel to each other. Spaced apart fourth and fifth slits 32positioned in a perpendicular orientation with respect to the substratewidth 42, each extends through the edge 46 of the substrate andintersect the three spaced apart parallel slits 32. It is noted thateach of the intersections of the parallel and perpendicular orientedslits 32 creates a cut-out portion 30 through the electricallyconductive substrate 24.

FIGS. 17 and 18 illustrate one or more embodiments in which two slits 32are arranged such that they intersect within the perimeter of thesubstrate 24. As shown in FIG. 17, the two slits 32 are arranged similarto that of the letter “X”. FIG. 18 illustrates a perpendicularlyoriented slit 32 that intersects a parallel oriented slit 32 withrespect to the substrate width 42. In one or more embodiments, the slitor slits 32 may be designed and oriented parallel to at least one trace82 of a coil 54, 20 of the receiving or transmitting antenna 12, 10. Inone or more embodiments, the at least one slit 32 may be oriented suchthat it extends towards or extends past at least one inductor coil trace82 of the receiving coil 54 or transmitting coil 20 when the substrate24 is oriented parallel to the respective inductor coil 20, 54. Asillustrated in FIG. 17, the respective ends of the at least one slit 32extend such that they are oriented parallel to the inductor coil trace82 of an outer inductor coil 86 of a receiving antenna 12. As shown inFIG. 18, the respective ends of the at least one slit 32 extend past theinductor coil trace 82 of an outer inductor coil 86 of a receivingantenna 12 positioned parallel to the substrate 24.

FIG. 19 illustrates a slit pattern comprising five slits 32 that extendfrom a central point. As shown, a first slit 126, a second slit 128, athird slit 130, and a fourth slit 132 are oriented at about a 90° anglefrom an adjacent slit. As illustrated, the first and second slit 126,128, the second and third slit 128, 130, the third and fourth slit 130,132 and the first and fourth slit 126, 132 are oriented aboutperpendicular to each other. A fifth slit 134 is positioned at about a45° angle between the third and fourth slits 130, 132. In one or moreembodiments, the fifth slit 134 may also be positioned at about a 45°angle between the first and second slits 126, 128 the second and thirdslits 128, 130 or the first and fourth slit 126, 132.

In addition to designing the electrically conductive substrate 24 witheither a cut-out 30 or a slit 32, the metallic substrate 24 may bedesigned with a combination of at least one cut-out 30 and at least oneslit 32. FIGS. 20 through 24 illustrate various embodiments of cut-outand slit patterns that may be comprised within the electricallyconductive substrate 24. FIG. 20 illustrates a slit 32 that extends froma cut-out 30 configured in a circular geometric shape. As shown, theproximal end 120 of the slit 32 extends from the perimeter 108 of thecut-out 30 through the substrate edge 46. FIG. 21 illustrates aplurality of slits 32 that radially extend from a cut-out 30 configuredhaving a circular geometric shape. As shown, eight slits 32 radiallyextend from the cut-out 30. As further shown, the proximal ends 120 ofthe eight slits 32 radially extend from the perimeter 108 of the cutout30. FIG. 22 shows eight slits 32 that radially extend from a cut-out 30configured in a circular geometry. A ninth slit 136 extends horizontallyacross one of the eight slits 32 that is oriented perpendicular. FIG. 23shows eight slits 32 that radially extend from a cut-out 30 configuredin a polygon geometry. As shown, the distal end 124 of four of the eightslits 32 extends towards the inductor coil trace 82 whereas the distalend 124 of three slits 32 extends past the inductor coil trace 82 of anadjacently positioned receiving or transmitting coil 54, 20. FIG. 24shows eight slits 32 that radially extend from a cut-out 30 configuredin a polygon geometry. As shown, all of the eight slits 32 extend towardthe inductor coil trace 82 positioned parallel to the substrate 24 anddo not extend past the inductor coil trace 82. In one or moreembodiments, the width 118 of the at least one slit 32 is less than thediameter of the cut-out 30.

In either case, in one or more embodiments, the electrically conductivesubstrate 24 may be configured to have an “area” that is 80 percent orgreater. As defined herein, “area” is the remaining surface area, inpercent, of the metallic substrate 24 after the substrate 24 has beenconfigured with the cut-out and/or slit pattern. “Area” is calculated bysubtracting the percent surface area of the cut-out and/or slit patternfrom the total surface area of the metallic substrate 24. For example,if a cut-out pattern comprises 10 percent of the total surface area ofthe metallic substrate 24 then the “area” is 90 percent (100% of themetallic surface area−10% of the surface area of the cut-outconfiguration). In one or more embodiments, an area that is 80 percentor greater mitigates the eddy current magnetic field by reducing theflux of the eddy current magnetic field in the cut-out/slit area. Also,an area that is 80 percent or greater increases the magnetic flux of theincident magnetic field 14 emanating from the transmitting antenna 10 inthe cut-out area of the electrically conductive substrate 24 positionedin parallel to the coil 54 of the receiving antenna 12, therebyincreasing mutual inductance between the transmitting and receivingantennas 10, 12.

In one or more embodiments, various electrical performance parameterswere measured in which the electrically conductive substrate 24,comprising various cut-out and slit patterns, were incorporated with areceiving antenna 12. One electrical parameter is quality factor (Q)defined below. The quality factor of a coil defined as:

$Q = \frac{\omega*L}{R}$

Where:

-   -   Q is the quality factor of the coil    -   L is the inductance of the coil    -   ω is the operating frequency of the coil in radians/s.        Alternatively, the operating frequency (Hz) may be ω divided by        2_(Π)    -   R is the equivalent series resistance at the operating frequency

Another performance parameter is resistance of receiver antennaefficiency (RCE) which is coil to coil efficiency. RCE is defined as:

${RCE} = \frac{k^{2}*Q_{Rx}*Q_{Tx}}{\left( {1 + \sqrt{\left( {1 + {k^{2}*Q_{rx}*Q_{tx}}} \right)}} \right)^{2}}$

Where:

-   -   RCE is the coil to coil efficiency of the system    -   k is the coupling of the system    -   Q_(rx) is the quality factor of the receiver    -   Q_(tx) is the quality factor of the transmitter

Another performance parameter is mutual induction (M). “M” is the mutualinductance between two opposing inductor coils of a transmitting andreceiving antenna, respectively. Mutual induction (M) is defined as:

$M = \frac{V_{induced}}{j*\omega*I_{Tx}}$

Where:

-   -   V_(induced) is induced voltage on the receiver coil    -   I_(tx) is the AC current flowing through the transmitter coil    -   ω is the operating frequency multiplied by 2_(Π)

Mutual inductance can be calculated by the following relationship:

M=k*√{square root over (L_(Tx) *L _(Rx))}

Where:

-   -   M is the mutual inductance of the system    -   k is the coupling of the system    -   L_(Tx) is the inductance of the transmitter coil    -   L_(Rx) is the inductance of the receiver coil

Another performance parameter is figure of merit (FOM). “FOM” is aquotient that indicates the efficiency of wireless electrical energybetween two opposing inductor coils of a transmitting and receivingantenna, respectively. Figure of Merit (FOM) is defined as:

FOM=k²Q_(rx)Q_(tx)

Where:

-   -   k is the coupling of the system    -   Q_(rx) is the quality factor of the receiving antenna    -   Q_(tx) is the quality factor of the transmitting antenna

The parameter of “effective area” is defined as the ratio of the area ofthe inductor coil that is not covered by the electrically conductivesubstrate comprising the at least one cut-out and slit. “Effective area”is defined as:

${{EFF}\mspace{14mu} {AREA}} = \frac{{Area}{\mspace{11mu} \;}{of}{\mspace{11mu} \;}{Resonator}\mspace{14mu} {Coil}{\mspace{11mu} \;}{Not}\mspace{14mu} {Covered}\mspace{14mu} {By}\mspace{14mu} {Substrate}}{{Area}{\mspace{11mu} \;}{Of}\mspace{14mu} {Resonator}\mspace{14mu} {Coil}}$

The parameter of “Area” is defined as the ratio of the combined surfacearea of the at least one cutout and slit within the electricallyconductive substrate to the surface area of the electrically conductivesubstrate without the at least one cutout and slit. “Area” is definedas:

${AREA} = \frac{A - 1}{B - 1}$

Where:

-   -   A is the combined surface area of the at least one cut-out and        slit within an electrically conductive substrate    -   B is the surface area of the electrically conductive substrate        without the at least one cut-out and slit formed within the        substrate.

TABLE I Cut- Configuration Configuration out/Slit ESR No. DescriptionFIG. L (μH) (mΩ) Q 1 Coil Only N/A 2.58 0.71 155.68 2 Coil + N/A 4.221.39 129.33 Ferrite 3 Coil + N/A 4.01 1.47 116.21 Ferrite + CopperBacking 4 Ferrite + N/A 0.92 1.00 39.19 Copper Backing + Metal Cover 5Ferrite + 7 0.95 1.02 39 Copper Backing + Metal Cover with Circular Hole6 Ferrite + 20 3.03 1.31 98.53 Copper Backing + Metal Cover withCircular Hole and rectangular slit 7 Ferrite + 21 2.70 1.41 81.57 CopperBacking + Metal Cover with Circular Hole and star slit

Table I above details various measured performance parameters of an NFMCsystem comprising a transmitting antenna 10 and a receiving antenna 12.A transmitting antenna 10 comprising an NC3-A Airfuel certified resonanttransmitting inductor coil 20 was used in the performance testing asdetailed in configurations 1-7 shown in Table I. The transmittingantenna 10 was configured having a solenoidal inductor coil with alength of 170 mm and a width of 105 mm and 6 turns. The receivingantenna 12 comprised a receiving inductor coil 54 having 8 number ofturns. The receiving inductor coil 54 was configured having a diameterof 34 mm. Test configuration 1 comprised only the receiving antenna 12with the receiving coil 54. Test configuration 2 comprised the receivingantenna 12 with the receiving coil 54 positioned on Kitagawa FFSXferrite material having a loss tangent of 110 and a thickness of 0.3 mmthat served as a magnetic field shield. In test configuration 3, thereceiving antenna 12 comprised a copper substrate having a thickness of0.055 mm positioned in contact with the side of the ferrite materialopposite the side that supported the receiving inductor coil 54 used intest configuration 2. Test configuration 4 comprised the receivingantenna 12 of test configuration 3 with the addition of an electricallyconductive substrate 24 composed of copper with a thickness of 0.5 mmpositioned proximal and parallel to the receiving coil 54. It is notedthat the electrically conductive substrate 24 in test configuration 4,did not comprise an opening through its thickness. A gap of 0.01 mmseparated the electrically conductive substrate 24 from the receivingcoil 54. The electrically conductive substrate 24 simulated a metalcover of an electronic device such as a cellular phone. Testconfiguration 5 comprised the previous test configuration 4 with theaddition of the electrically conductive substrate 24 having a circularcut-out 30 with a diameter of 21 mm extending through its thickness asillustrated in FIG. 7. The planar surface of the electrically conductivesubstrate 24 comprising the circular cut-out 30 was positioned proximalto and parallel to the receiving coil 54. The diameter or perimeter 108of the cut-out 30 was of the same size and dimension as the innerdiameter of the receiving coil 54. In addition, the electricallyconductive substrate 24 comprising the circular cut-out 30 was orientedparallel to the receiving coil 54 such that an imaginary line orientedperpendicular therebetween was tangent to the perimeter 108 of thecut-out 30 and tangent to the inner diameter of the receiving coil 54.Test configuration 6 comprised the receiving antenna 12 as configured intest configuration 5 with the addition of a slit 32 that extendedthrough the thickness of the electrically conductive substrate 24 fromthe perimeter 108 of the circular cut-out 30 through the side edge 46 ofthe electrically conductive substrate 24 as illustrated in FIG. 20. Theslit 32 was configured with a width of about 3 mm and a length of about12 mm. Test configuration 7 comprised the receiving antenna 12 asconfigured in test configuration 4 with the electrically conductivesubstrate 24 further comprising a cut-out pattern in the shape of astar, as illustrated in FIG. 21, formed through its thickness. The starcut-out pattern comprised eight slits 32 each having a width of about 3mm radially extending from a circular hole having a diameter of 21 mm.One of the slits 32 extended through the side edge 46 of theelectrically conductive substrate 24.

It is noted that the inductance values detailed in Table I were measuredinductance values of the receiving antenna in free space measured withan Agilent 4294A precision impedance analyzer at an operating frequencyof 6.78 MHz. The equivalent series resistance (ESR) values in Table Ilist the measured ESR values of the receiving antenna in free spacemeasured with an Agilent 4294A precision impedance analyzer at anoperating frequency of 6.78 MHz. The quality factor values listed inTable I were of the receiving antenna 12 at an operating frequency of6.78 MHz.

As shown in Table I above, positioning an electrically conductivesubstrate 24, such as a metal cover, in front of the receiving coil 54of the receiving antenna 12, as tested in configuration 4, significantlyreduced the inductance and quality factor. In addition, equivalentseries resistance (ESR) increased in comparison to test configuration 1comprising only the receiving antenna 12. This increase in ESR andreduction in inductance and quality factor is the result of theformation of the opposing secondary magnetic field 18 created by theeddy current on the surface of the electrically conductive substrate 24as previously discussed.

TABLE II Test FIG. L R K M RCE Eff Area Area No. No. (μH) (mΩ) Q (%) FOM(nH) (%) (%) (%) 1 Outer Coil 0.72 0.46 66 7.7 95.99 220 78 N/A N/A 2Inner and 6.01 3.42 74 6.0 66.1 500 73 N/A N/A Outer Coil 3 12 0.94 83447 2.6 7.8 85 31.3 12.3 94.6 4 15 1.20 858 59.2 7.1 73.8 264 74.5 17.192.3 5 16 1.25 916 58.4 7.3 76.4 276 75.9 21.9 89.1 6 17 0.68 767 37.41.3 1.4 35 10 9.2 96.0 7 18 1.00 764 55 6.4 56.1 218 72 9.3 96.0 8 200.93 700 56.5 5.6 43.2 182 68.3 6.1 — 9 20 1.65 783 90 11.5 292.8 50089.1 100 79.4 10 21 1.17 866 58.7 7.7 85.7 282 77 21.4 91.5 11 21 1.3903 61 8.2 100.0 315 83 46.9 — 12 22 1.24 893 59 6.6 63.9 250 74 46.9>80    13 23 1.16 862 57.2 7.5 78.3 272 75.8 19.3 92.2 14 23 1.44 89568.6 9.8 161.2 397 86.3 32.8 93.4 15 23 1.35 903 63 8.9 122.7 350 84.925.8 94.8 16 24 1.15 832 58.8 8.4 102.1 305 78.6 16.9 93.8

Table II above details the measured performance parameters of a nearfield magnetic coupling (NFMC) system comprising a transmitting antenna10 and a receiving antenna 12. In one or more embodiments, a metallicsubstrate 24 configured with various cut-out and slit patterns, asdetailed in Table II above was positioned in parallel with a receivingantenna coil 54 such that the substrate 24 was positioned between thereceiving coil 54 of the receiving antenna 12 and the transmittingantenna 10.

In one or more embodiments, the transmitting antenna 10 for all testNos. 1-16, comprised an NC3-A Airfuel certified resonant transmittingcoil. The transmitting antenna 10 was configured having a solenoidalinductor coil with a length of 170 mm and a width of 105 mm and 6 turns.It is noted that the “outer coil” configuration, test No. 1, detailed inTable II above, comprised only a receiving antenna 12 having a receivingcoil 54 with a length of 73 mm, a width of 55 mm and 5 turns. The “innerand outer coil” configuration, test No. 2, detailed in Table II abovecomprised a receiving antenna 12 with only an outer coil having a lengthof 73 mm, a width of 55 mm and 5 turns and an inner coil electricallyconnected in series to the outer coil. The inner coil was configuredhaving a diameter of 34 mm and 10 turns. Test Nos. 3-8 comprised areceiving antenna 12 configured with an outer coil having a length of 73mm, a width of 55 mm and 5 turns. Test Nos. 9-16 comprised a receivingantenna 12 configured with an outer coil having a length of 73 mm, awidth of 55 mm with 5 turns and an inner coil electrically connected inseries to the outer coil. The inner coil was configured having adiameter of 66 mm and 5 turns. The receiving antenna 12 of Test Nos.3-16 also comprised a copper backing substrate and Kitagawa Industries'FFSX ferrite material having a loss tangent of about 110 that served asa magnetic field shield. The ferrite material served as the substrate onwhich the receiving coil 54 was positioned. The copper backing substratewas positioned in contact with the ferrite material opposite the sidesupporting the receiving inductor coil 54. The ferrite material had athickness of 0.35 mm, and the copper backing substrate had a thicknessof 0.055 mm.

A copper substrate 24 having a thickness of about 0.5 mm configured withvarious cut-out and slit patterns correlating to the figure number,shown in Table II was positioned proximal to the receiving coil 54. Morespecifically, the metallic substrate 24 configured with the cutoutand/or slit pattern was positioned proximal and oriented in parallel tothe inductor receiving coil 54. In addition, configurations of Test Nos.3-16 comprising a metallic substrate 24 having a cut-out 30, theperimeter 108 of the cut-out 30 was positioned in alignment with theinner diameter of the inner receiving inductor coil 84 of the receivingantenna 12.

It is noted that the inductance values detailed in Table II were themeasured inductance values of the receiving antenna 12 in free space atan operating frequency of 6.78 MHz. The equivalent series resistance(ESR) values detailed in Table II were the measured ESR values of thereceiving antenna 12 in free space at an operating frequency of 6.78MHz. The quality factor values listed in Table II were of the receivingantenna at an operating frequency of 6.78 MHz. The inductance and ESRvalues were measured with an Agilent 4294A precision impedance analyzer.It is also noted that the symbol “−” indicates that a measurement wasnot taken.

As detailed in Table II, utilization of the metallic substrate 24configured with the cut-out and slit pattern shown in FIG. 20 exhibitedthe greatest mutual inductance, FOM, and RCE. This increased performanceis attributed to the combination of the cut-out and slit patternillustrated in FIG. 20. Specifically, the perimeter 108 of the cut-out30 is dimensioned in a circular shape and aligned with the innerdiameter of the interior coil 84 of the receiving antenna 12. Inaddition, the slit 32 radiating from the perimeter 108 of the cut-out 30and extending through the edge 46 of the substrate 24 is attributed tohave disrupted the eddy current and thus minimized the magnitude of theopposing secondary magnetic fields.

TABLE III Gap Distance (mm) RCE (%) 1.0 87 0.5 89 0.0 92

Table III above illustrates how the size of the gap 56 between theelectrically conductive substrate 24, comprising the at least onecut-out 30 and slit 32, and the inductor coil 54 of the receivingantenna 12 affects RCE between the transmitting and receiving antennas10, 12. In one or more embodiments, the transmitting antenna 10comprised an NC3-A Airfuel certified resonant transmitting coil. Thetransmitting antenna 10 was configured having a solenoidal inductor coilwith a length of 170 mm and a width of 105 mm and 6 turns. The receivingcoil 54 was configured having a coil with a diameter of 34 mm with 8turns.

The receiving antenna 12 also comprised a copper backing substrate andFFSX-3 ferrite material having a loss tangent of 110 that served both asthe substrate supporting the receiving coil 54 and magnetic fieldshield. The copper substrate was positioned in contact with the side ofthe ferrite material opposite the side supporting the receiving coilconfiguration. The ferrite material had a thickness of 0.35 mm, and thecopper backing substrate had a thickness of 0.055 mm. A plastic spacer68 was positioned between the electrically conductive substrate 24comprising the cutout/slit pattern, as illustrated in FIG. 19, and thereceiving coil 54. Spacers 68 having different thicknesses were used tocontrol the gap distance as detailed in Table III.

As indicated in Table III above, the RCE between the transmittingantenna 10 and the receiving antenna 12 increases as the gap 56 betweenthe electrically conductive substrate 24 comprising the cut-out/slitpattern and the receiving antenna coil 54 decreases. As shown, the RCEincreased from about 87 percent to about 92 percent as the gap 56between the receiving coil 54 and metallic substrate 24 decreased fromabout 1 mm to about 0 mm.

FIGS. 25 and 26 are plots that illustrate embodiments of the eddycurrent density (Joule Ampere/m²)(FIG. 25) and eddy current densityvector (FIG. 26) taken from a computer simulation of an embodiment of anelectrically conductive substrate 24 comprising a circular cut-out 30.The legend 138 illustrates the relative intensity of the eddy currentdensity along the surface of the simulated metallic substrate 24 inJoules Ampere/m². It is noted that the checkered pattern surrounding thesimulated eddy current densities shown in FIGS. 25 through 28 is anartifact of the computer simulation.

FIG. 25 illustrates the simulation of the eddy current density (JoulesAmpere/m²) along the surface of an electrically conductive substrate 24comprising a circular shaped cut-out 30. It is noted that the darkenedintensity about the center of the plot, where the “x” and “y”co-ordinate arrows intersect, is an artifact of the computer simulationas the “z” co-ordinate, coming out of the plane of the plot,artificially creates a dark area about the center of the plot. As shown,the eddy current density (Joule Ampere/m²) is strongest along the edgeof the substrate 24. The eddy current density is weakest about thecenter of the plot, where the “x” and “y” co-ordinate arrows intersect.As further illustrated in the simulation, the eddy current density iszero within the circular cut-out 30. This, therefore, enables theincident magnetic field 14 emanating from the transmitting antenna 10 topass therethrough. In addition, as shown in FIG. 26, the eddy current 15flows in a clockwise direction about the circular shaped cut-out 30. Itis noted that removing surface area from the electrically conductivesubstrate 24 that is not aligned with the receiving inductor coil 54,tends to increase the eddy current density on the surface areas of thesubstrate 24. This tends to increase the strength of the opposing eddycurrent secondary magnetic fields 18 that generally leads to a reductionin mutual inductance and coupling.

FIGS. 27 and 28 illustrate a further embodiment of the eddy currentdensity (FIG. 27) and eddy current density vector (FIG. 28) taken from acomputer simulation. In this embodiment, the simulated electricallyconductive substrate 24 comprises a circular shaped cut-out 30 and aslit 32 that radially extends from the perimeter 108 of the circularshaped cut-out 30 through the substrate edge 46. In this embodiment, asshown in FIG. 28, the eddy current 15 is flowing in a counter-clockwisedirection about the circular shaped cut-out 30.

FIG. 27 illustrates the simulation of the eddy current density (JouleAmpere/m²) along the surface of an electrically conductive substrate 24comprising the circular shaped cut-out 30 and the slit 32 that radiallyextends from the cut-out 30 and extends through the substrate edge 46.It is noted that the darkened intensity about the center of the plot,where the “x” and “y” co-ordinate arrows intersect, is an artifact ofthe computer simulation as a “z” co-ordinate, coming out of the plane ofthe plot, artificially creates a dark area about the center of the plot.As shown in the plot, the eddy current density is strongest along theperimeter 44 of the substrate 24. The eddy current density is weakestabout the center of the plot, where the “x” and “y” co-ordinate arrowsintersect. As further illustrated in the simulation, the eddy currentdensity significantly decreases in a radial fashion from the cut-outperimeter 108 along the substrate surface 36. The significant decreasein eddy current density outwardly extending from the perimeter 108 ofthe cut-out 30 is attributed to the slit 32 that radially extends fromthe perimeter of the cut-out 30 extending through the edge 46 of thesubstrate 24. Similar to FIG. 25, the eddy current density within thecut-out 30 is zero. Therefore, as shown in the simulation, the eddycurrent does not flow within the cut-out 30 and therefore allows for theincident magnetic field 14 emanating from the transmitting antenna 10 topass therethrough. Furthermore, configuring the electrically conductivesubstrate 24 having a circular shaped cut-out 30 and slit 32 extendingthrough the substrate edge 46, as shown in FIGS. 27 and 28,significantly reduces the eddy current density in an outward radialdirection from the cut-out 30. Thus, the strength of the eddy current issignificantly reduced in the area surrounding the cut-out 30 which isaligned with the adjacent receiving inductor coil 54 of the receivingantenna 12 as previously discussed. Thus, interference caused by theeddy current 15 is reduced in the area that surrounds the cut-out 30.This, therefore, allows an increased magnitude of the incident magneticfield 14 from the transmitter antenna 10 to pass therethrough, whichthus allows for an increase in wireless electrical energy through anelectrically conductive substrate 24.

In addition, as illustrated in FIG. 28, due to the slit 32, the eddycurrent 15 around the cut-out 30 is now flowing in a counter-clockwisedirection, i.e., in the same direction as the direction of the currentfrom the transmitting antenna coil 20. Therefore, the magnitude of theincident magnetic field 14 around the cut-out region is not only“maintained,” but is also increased. Since there is some increase in themagnitude of the incident magnetic field 14 due to the cut-out and slitpattern, it is understood that bringing the receiving antenna coil 54closer to the electrically conductive substrate 24 comprising thecut-out and slit pattern, will also increase the coupling, mutualinductance and RCE of the NFMC antenna system. It is noted that thesesimulation results correlate to the experimental results shown in TableII in which a circular cut-out and slit pattern, shown in FIG. 20, alsoexhibited an increase in coupling, mutual inductance, and RCE.

FIG. 29 illustrates an embodiment of the path of the eddy current 15taken from the computer simulation of the embodiment illustrated inFIGS. 27 and 28 simulating an electrically conductive substrate 24comprising a circular shaped cut-out 30 and slit 32 that radiallyextends from the perimeter 108 of the circular shaped cut-out 30 throughthe substrate edge 46. In this embodiment, a simulated single loopinductor coil 54 was used as the receiving antenna 12. It is noted thatthis embodiment is a representation of the maximum intensity of the eddycurrent. As shown, the flow of the eddy current 15 along the surface ofthe substrate 24, represented by first loop 140, is clockwise, while thecurrent flow of the eddy current about the cut-out 30, represented bysecond loop 142 is counter-clockwise due to the slit 32. Thus, thesimulation illustrates that the slit 32 radially extending from thecut-out 30 and extending through the substrate edge 46 modifies thedirection of the eddy current about the cut-out in a counter-clockwisedirection, which is the same directional flow of the electrical energywirelessly transmitted from a transmitting antenna 10. Therefore, sincethe direction of the eddy current 15 about the cut-out 30 and theelectrical energy wirelessly transmitted from the transmitting antenna10 are the same, i.e., counter-clockwise, the interaction of theincident magnetic field and the secondary magnetic field caused by theeddy current about the cut-out 30 is minimized. Thus, electrical energywirelessly transmitted by NFMC from a transmitting antenna 10efficiently passes through an electrically conductive materialcomprising the cut-out 30 and slit 32 configuration.

FIG. 30 illustrates an embodiment of the intensity of the magnetic fieldin Ampere per meter oriented perpendicular to the embodiment of FIG. 29.A legend 144 shows the intensity of the magnetic field perpendicular tothe surface of the substrate 24. As shown in the simulation, the maximumintensity of the eddy current decreases a distance away from thesubstrate 24. However, the magnetic field, having a counter-clockwiserotation, is strong at the center of the circular shaped cut-out 30 andslit 32. Thus, as the simulation illustrates, the electricallyconductive substrate configured with the cut-out 30 and slit 32minimizes interaction of the incident magnetic field 14 with thesecondary eddy current magnetic field 18. As a result, the magnitude ofthe incident magnetic field 14 through the cut-out 30 and slit 32pattern is maximized and the efficiency of wireless transmission ofelectrical energy through the electrically conductive substrate 24 isincreased.

Thus, it is contemplated that the electrically conductive substrate 24of the present disclosure is capable of being configured having avariety of unlimited cut-out and/or slit patterns. Furthermore, such aconfiguration of the variety of unlimited cut-out and/or slit patternsallows for and significantly improves the wireless transmission ofelectrical energy through an electrically conductive material. It isfurther contemplated that the various magnetic shielding materials 34can be strategically positioned adjacent to the antenna 10, 12 and theelectrically conductive substrate 24 configured with the various cut-outand/or slit patterns to enhance quality factor and mutual inductancebetween adjacently positioned transmitting and receiving antennas 10,12. It is appreciated that various modifications to the inventiveconcepts described herein may be apparent to those of ordinary skill inthe art without departing from the spirit and scope of the presentdisclosure as defined by the appended claims.

As used herein, the phrase “at least one of” preceding a series ofitems, with the term “and” or “or” to separate any of the items,modifies the list as a whole, rather than each member of the list (i.e.,each item). The phrase “at least one of” does not require selection ofat least one of each item listed; rather, the phrase allows a meaningthat includes at least one of any one of the items, and/or at least oneof any combination of the items, and/or at least one of each of theitems. By way of example, the phrases “at least one of A, B, and C” or“at least one of A, B, or C” each refer to only A, only B, or only C;any combination of A, B, and C; and/or at least one of each of A, B, andC.

The predicate words “configured to”, “operable to”, and “programmed to”do not imply any particular tangible or intangible modification of asubject, but, rather, are intended to be used interchangeably. In one ormore embodiments, a processor configured to monitor and control anoperation or a component may also mean the processor being programmed tomonitor and control the operation or the processor being operable tomonitor and control the operation. Likewise, a processor configured toexecute code can be construed as a processor programmed to execute codeor operable to execute code.

A phrase such as “an aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations.An aspect may provide one or more examples of the disclosure. A phrasesuch as an “aspect” may refer to one or more aspects and vice versa. Aphrase such as an “embodiment” does not imply that such embodiment isessential to the subject technology or that such embodiment applies toall configurations of the subject technology. A disclosure relating toan embodiment may apply to all embodiments, or one or more embodiments.An embodiment may provide one or more examples of the disclosure. Aphrase such an “embodiment” may refer to one or more embodiments andvice versa. A phrase such as a “configuration” does not imply that suchconfiguration is essential to the subject technology or that suchconfiguration applies to all configurations of the subject technology. Adisclosure relating to a configuration may apply to all configurations,or one or more configurations. A configuration may provide one or moreexamples of the disclosure. A phrase such as a “configuration” may referto one or more configurations and vice versa.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” or as an “example” is not necessarily to be construed aspreferred or advantageous over other embodiments. Furthermore, to theextent that the term “include,” “have,” or the like is used in thedescription or the claims, such term is intended to be inclusive in amanner similar to the term “comprise” as “comprise” is interpreted whenemployed as a transitional word in a claim. Furthermore, to the extentthat the term “include,” “have,” or the like is used in the descriptionor the claims, such term is intended to be inclusive in a manner similarto the term “comprise” as “comprise” is interpreted when employed as atransitional word in a claim.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. § 112, sixth paragraph, unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor.”

Reference to an element in the singular is not intended to mean “one andonly one” unless specifically so stated, but rather “one or more.”Unless specifically stated otherwise, the term “some” refers to one ormore. Pronouns in the masculine (e.g., his) include the feminine andneuter gender (e.g., her and its) and vice versa. Headings andsubheadings, if any, are used for convenience only and do not limit thesubject disclosure.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of what may be claimed, but ratheras descriptions of particular implementations of the subject matter.Certain features that are described in this specification in the contextof separate embodiments can also be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment can also be implemented in multipleembodiments separately or in any suitable sub combination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to a subcombination or variation of a sub combination.

What is claimed is:
 1. A method of making an antenna, the methodcomprising the following steps: a) forming at least one inductor coilpositioned on a first substrate, the at least one inductor coil havingan inner inductor coil diameter; b) positioning a second substrateadjacent to the at least one inductor coil, the second substrate havinga second substrate surface extending to a second substrate perimeterhaving an end defining a second substrate surface area and having asecond substrate thickness oriented about perpendicular to the secondsubstrate surface; c) forming a cut-out within the second substratesurface, the cut-out configured having a cut-out perimeter defining acut-out shape oriented parallel to the second substrate surface, thecut-out extending through the second substrate thickness, wherein theperimeter of the cut-out is oriented in parallel with the inner diameterof the at least one inductor coil; and d) forming at least one slithaving a slit length extending from a slit proximal end to a slit distalend, a slit width oriented perpendicular to the slit length, and a slitdepth extending at least partially within the second substratethickness, wherein the slit proximal end extends from the cut-outperimeter, the slit distal end extending towards a second substrateedge.
 2. The method of claim 1 wherein the slit depth extends throughthe second substrate thickness.
 3. The method of claim 1 furtherconfiguring the cut-out shape in a geometric shape selected from thegroup consisting of a circle, an oval, a rectangle, a square, atriangle, an octagon, and a polygon.
 4. The method of claim 1 furthercomprising the second substrate of an electrically conducting material.5. The method of claim 1 further configuring the second substrateaccording to the equation:$\frac{A - 1}{B - 1} > {80\mspace{14mu} {percent}}$ where A is acut-out pattern surface area defined by combined surface areas of thecut-out and the at least one slit and B is the surface area of thesecond substrate without the cut-out and the at least one slit withinthe second substrate.
 6. The method of claim 1 wherein the length of theat least one slit ranges from about 1 mm to about 50 mm.
 7. The methodof claim 1 wherein the width of the at least one slit ranges from about1 mm to about 5 mm.
 8. The method of claim 1 wherein the distal end ofthe at least one slit resides at the second substrate edge.
 9. Themethod of claim 1 further extending the distal end of the at least oneslit through the second substrate edge.
 10. The method of claim 1wherein the antenna is configured to receive or transmit wirelesselectrical energy via near field magnetic coupling.
 11. The method ofclaim 1 wherein the antenna comprises a self resonance frequency equalto or greater than 1.5 times an antenna operating frequency.
 12. Themethod of claim 1 further electrically incorporating the antenna with anelectric device.
 13. The method of claim 12 wherein the electronicdevice is selected from the group consisting of a cellular phone, acomputer, a radio, a television, a medical device, and a device thatcomprises an electronic circuit.
 14. The method of claim 1 wherein thesecond substrate comprises a sidewall of an electronic device.
 15. Themethod of claim 1 further positioning a gap between the at least oneinductor coil and the second substrate.
 16. The method of claim 15wherein the gap ranges from about 0.1 mm to about 10 mm.
 17. The methodof claim 1 further positioning a spacer comprising a polymeric materialbetween the at least one inductor coil and the second substrate.
 18. Themethod of claim 1 wherein the first substrate comprises a ferritematerial.
 19. The method of claim 18 wherein the ferrite materialcomprises a loss tangent equal to or less than about 0.70.
 20. Themethod of claim 1 further forming an opening that extends through athickness of the first substrate, the at least one inductor coilpositioned surrounding the opening.
 21. The method of claim 1 whereinthe first substrate comprises an overhang portion that circumferentiallyextends around an outer diameter of the at least one inductor coil. 22.The method of claim 1 further positioning a third substrate comprisingan electrically conductive material adjacent to a surface of the firstsubstrate opposite the at least one inductor coil.
 23. The method ofclaim 22 wherein the third substrate comprises copper, nickel, aluminumor a combination thereof.
 24. The method of claim 1 further aligning thecut-out and the inductor coil so that an imaginary line orientedperpendicular therebetween extends through a perimeter of the cut-outand an inner diameter of the at least one inductor coil.